In the field of electron microscopy, biological material in the form of very small pieces of tissue approximately 1 millimeter square (specimens) are embedded in polymeric substances such as epoxy or methacrylate resins. These resins are then hardened into rod-like shapes by exposure to heat or ultraviolet radiation, while in polyethylene molds such as the well known BEEM(copyright) capsule. When the capsule is removed, these hardened rods present the specimen at the apex of a pyramid, the face of which is approximately 1 millimeter square. The rods are called specimen blocks or simply blocks by electron microscopists. The blocks are placed in an ultramicrotome, where thin sections approximately 66-90 millimicrons thick are cut from the pyramidal face and mounted on xe2x85x9xe2x80x3 diameter copper grids for viewing in the electron microscope. While much attention has been paid to devices for the safe storage of the grids (see U.S. Pat. No. 3,353,656 and U.S. Pat. No. 3,768,914), little has been done to provide the same protection, identification and organization for the blocks. The specimen-bearing tips of these blocks are vulnerable to damage prior to sectioning, and even more vulnerable after sectioning when the tissue inside has been exposed.
At present, no commercially available block storage system exists other than the BEEM(copyright) modular specimen storage receptacle (U.S. Pat. No. 3,353,656) that allows for the safe storage and identification of these blocks. This early BEEM(copyright) modular storage receptacle, while effective, has two drawbacks:
(1) it is a low volume device, providing space for only two blocks while there are usually many blocks associated with a given experiment.
(2) the two blocks merely xe2x80x98restxe2x80x99 in their cavities and can be inadvertently dislodged whenever the module is open.
The present invention serves to overcome the above shortcomings, and is embodied in and carried out by a block storage module containing a plurality of shaped cavities into which the blocks xe2x80x9csnapxe2x80x9d, i.e., are mechanically held in place by structural projections or detents formed on the cavity walls at or near the open end of the cavity, thus eliminating the possibility of inadvertent dislodgement. Each cavity is indexed by letter and number providing for the rapid, accurate identification of every individual block. Each of the modules has on its undersurface a pressure sensitive adhesive which permits the module to be attached to any appropriate surface; i.e., the inside bottom of a fitted box, or in any combination desired onto a specially-designed and suitably-sized (e.g., 8xe2x80x3xc3x9711xe2x80x3) panel that fits into a protective binder (e.g., a standard three-ring binder) for holding a plurality of the panels in any desired order. Many such panels can be stored in a single binder, separated by indexed dividers on which any relevant data can be recorded, and, as a consequence of the xe2x80x9csnap-inxe2x80x9d feature, the binders can be stored in an upright position without fear of the blocks becoming dislodged. The panels are each preferably covered with an overlying cover that is secured both to the binder and to the associated panel. Each cover is preferably clear to enable the user to read the indicia on the underlying modules. This arrangement provides a safe, compact, and infinitely expandable high-volume specimen storage system.